When you realize exactly what this world-existence is, you will want to abandon, relinquish and renounce it completely.
To study Zen is to study this world-existence with the intent of ‘knowing what it is, because you have to know what it is to escape what it is.
To escape, you cannot cling to anything. For if you do, that one thing you cling to will drag you right back into this world-existence.
How to escape? How to know this world-existence? how to study Zen? Sure, books can help to an extent, though you many need to find a Zen Master who knows The Way Out and ask them a few questions